CC-Link unveils 1Gbps industrial ethernet at the field/device level
24 Nov 2009
Nuremberg, Germany - CC-Link, the open communications protocol for industrial automation, is now available with 1Gbps Industrial Ethernet (IE) at the field/device level, complementing the controller level IE network launched less than a year ago.
The development is intended to enable manufacturers to integrate all data into a single information system encompassing commercial and production requirements, from IT systems in the boardroom to field devices on the manufacturing floor. This vertical integration will optimise production performance, against the needs of distribution, commerce and marketing, claims C-C Link.
CC-Link IE is a family of integrated Industrial Ethernet-based networks designed for high performance deterministic control. Originally launched at the controller level, the concept has now been extended to field networks. It uses Ethernet to transfer data around and between the various networks that make up a control system. Communication is seamless between the networks, so that there is no hierarchy or any boundaries within the network.
The CC-Link IE controller network is a high reliability trunk network for large scale controller-distributed control. It operates over a 1Gbps deterministic network using full duplex optical fibre. It has a ‘floating’ network master to maintain stable operations, automatic cable error detection and many other features.
The new CC-Link IE field network is also a 1Gbps deterministic network but over Cat 5e cable. This network offers the necessary connectivity for both existing and new types of manufacturing management. CC-Link IE Controller and CC-Link IE Field can be used together or independently, and both will integrate with the existing CC-Link and Safety networks.
The CC-Link IE field network has been developed to enable the easy transfer of high speed control data and large scale message communication capability across networks with determinism and minimal latency. To achieve this, control data uses cyclic communication and a distributed shared memory, while messaging data uses transient/acyclic communication.
Cyclic communication refreshes the control data among all the stations by using token passing as media access control. Through the distributed shared network memory, each controller: exchanges data with all other controllers; recognises the condition of other controllers, and performs its own control actions. As control data is exchanged in real time, it supports deterministic control.
This means that in user applications, communication design is possible simply by reading from, or writing to the shared memory. Any device connected to the network can send and receive data from the shared memory and therefore no specific CC-Link IE protocol knowledge is required.
Transient communication
CC-Link also highlighted how the IE field network also provides for direct peer-to-peer transient/acyclic communication between network stations for non-deterministic messaging. This process does not affect the cyclic real-time operation of the network as CC-Link IE assigns a relatively small portion of transmission bandwidth for transient communication.
Any device connected to the network can send and receive data from this common letterbox and therefore no specific CC-Link IE protocol knowledge is required. This function has a seamless one to-many relationship so creating a control program that is logically a single hierarchy network regardless of physical configuration, added a C-C LInk statement.
The IE field network is designed to access field devices for configuration and maintenance purposes right across the network hierarchy by remote engineeringtools. Remote management means that devices can be set or monitored from anywhere in the network. CC-Link IE field networks can use line, star, ring and tree topologies with up to 254 devices per network. Further, up to 239 networks can be connected together, providing sufficient scalability for any purpose.
New stations, meanwhile, can be connected freely either to an empty port of a hub, or to a port on an existing station, by using unmanaged hubs. The physical and data link layers of the network use standard Ethernet so that commercial Ethernet cables, hubs and network analysers can be used.
The “seamless communication function” of the CC-Link family is achieved over TCP/IP through an application common protocol called SLMP. Since the SLMP is a simple client/server protocol it can be easily implemented into firmware for 100Mbps Ethernet devices by third-party vendors, and then connected as shown below. The device can then access devices across the CC-Link IE field network.
